The disclosure relates to an angular position and speed dependent sensing system, particularly for sewing machines, utilizing multiple impulse transmitter means securely fastened to the main shaft of the sewing machine which is to be controlled.
Angular position and speed dependent sensing systems are well known from prior art. They are widely used especially in sewing machines in order to stop the needle in a predetermined position and to control other movements of the sewing machine. Examples of this would be cutting of the thread or lifting of the presser foot.
Among these known sensing systems some employ impulse transmitter means which release certain functions, i.e., positioning of the needle or thread cutters. Because these operations are releasable only at a predetermined speed, a tachometer generator is needed. The tachometer generator indicates the predetermined speed via a comparator.
These previously known control systems are relatively expensive, because the angle positioning device and the tachometer generator are two separate structures with only the outlet connecting both units. It has been proposed to combine the impulse transmitter means and the tachometer generator means into one unit thus measure revolutions; however, this has had no great influence on the relatively high cost of the above mentioned control system.